The present invention relates to methods of dehydrating, passivating, sealing of refrigeration systems and a method for delivering combination of a binding azeotrope of methanol and cyclohexanone, a drying agent, a moisture activated metal treatment and rubber rejuvinating compound into a single container.
The present invention generally relates to the maintenance of air conditioning or refrigeration systems and, in a preferred embodiment thereof, more particularly relates to apparatus and methods for placing an additive fluid in to the refrigerant circuit of an air conditioning system.
In the typical air conditioning or refrigeration system it is often necessary to place an additive fluid (normally a liquid) into the refrigerant circuit portion of the system to maintain the performance of the system at a satisfactory level. Examples of additive fluids placed in refrigerant circuits include compressor oil, stop-leak liquid, acid neutralizers, drying agents, and ultraviolet colored leak-finder liquid.
Additive fluids of these and other types are conventionally placed in refrigerant circuits by one of four methodsxe2x80x94namely, (1) the refrigerant circuits by one of four methods (2) the additive fluid is placed in a container along with pressurized refrigerant and is expelled with the pressurized refrigerant into the circuit; (3) the additive fluid is placed in an in-line storage device, and pressurized refrigerant is flowed through the storage device to force the additive fluid into the circuit along with the pressurized refrigerant; or (4) the additive fluid is injected into the circuit using a mechanical piston to force the fluid into the circuit.
These conventional techniques carry with them certain known problems, limitations and disadvantages. For example, to simply open the refrigerant circuit and pour the additive in can undesirably cause release of refrigerant to the atmosphere, and can also undesirably introduce contaminating air into the circuit. Packaging an additive fluid in a container with pressurized refrigerant to be forcibly injected into the circuit is also undesirable due the expense of adding refrigerant to the container as a propellant, the safety concerns inherent in a pressurized container structure, and the need to match the refrigerant propellant with the type of refrigerant within the circuit. Placing the additive fluid in an in-line device requires that the refrigerant forced through the device match the refrigerant in the circuit to avoid contamination of the circuit. Injecting additive fluid into a refrigerant circuit using a mechanical piston device tends to be a somewhat cumbersome task requiring specialized packaging and/or equipment.
Recently, severe restrictions by the U.S. Government has been placed on use of chlorofluorocarbons (CFCs) due to environmental problems which are as a result of the destruction of stratospheric ozone. In addition, CFCs have been labeled as environmentally unsafe in many countries worldwide. As a result, proposed alternative substances which can be substituted for CFCs in various applications have been and are being developed. Among them are several new proposed hydrofluorocarbons (HFCs). A substitution which is being used is HFC-R134a and related compounds. These materials are being sold as a substitutes for CFC as a refrigerant liquid for CFC as refrigeration fluids. These replacement materials, while not ozone-depleting continue to contribute in part to the greenhouse effect. Their use and escape into the atmosphere is the subject of the EPA""s Significant New Alternatives Programs, which limits the use of fluroinated compounds as alternatives for ozone-depleting chemicals.
The HFC replacement fluids are generally not as efficient as CFCs and require new types of additives including fluids, sealants, metal and rubber sealants as well as dehydrates and others. In addition, redesign of compressive-evaporative refrigeration and other systems using the HFCs has been necessary. The newer working fluid refrigerants exhibit different soluabilities than CFCs, and are not mixable with well known lubricants in CFC systems as well as other additives. For example, in a modern system using these compounds in cooperation with known lubricants causes hydrolysis of the lubricating esters in a chemical reversion process. Further, other chemical additives in the new environmental partially safe system cause additional metal and rubber leakage which, again, can bring on additional problems for the FPA and the environment.
Leaks allow refrigerants and other working fluids to escape into the atmosphere, contaminating the environment and decreasing the efficiency and cooling capacity of the unit. If large amounts of cooling working fluids such as refrigerants escape, the system may overheat and the service life of the unit will thereby be shortened. Further, the unit may suffer mechanical failure from the loss of the working fluid. In general, leaks in heating and cooling systems also decrease the heat transfer efficiency of these systems.
Water in all types of compressive-evaporative systems decreases the system efficiency as a result of water""s high heat of vaporization and high heat capacity. The high heat of fusion of water decreases the efficiency of a compressive-evaporative system by giving off heat in evaporation cycles as the water freezes. The resulting ice crystals can also block orifices in expansion valves and cause such systems to malfunction.
A need continues to exist in the art for a method for sealing leaks in refrigeration, air conditioning, heating and ventilation and related systems and for the complete dehydration of the systems. More importantly, there is a need that exist in the prior art for the addition in a one-step application of a drying agent, a moisture activated metal treatment and a rubber rejuvinating compound in a single container in combination with a binding azeotrope.
As can readily be seen from the foregoing, a need exists for improved apparatus, methods for placing additive fluids and said additive fluids into a refrigerant circuit. It is to this need that the present invention is directed.
In carrying out principles of the present invention, in accordance with a preferred embodiment thereof, a specially designed vessel or canister is provided for use in placing an additive fluid, representatively an additive liquid, into the refrigerant circuit of an air conditioning or refrigeration system, representatively an automotive air conditioning system. In a preferred embodiment thereof, the vessel has an interior communicatable with a suction line portion of the refrigerant circuit, the vessel interior being partially filled with an additive liquid, being partially evacuated to a vacuum pressure less than that of the suction line portion during operation of the air conditioning system, and being substantially devoid of refrigerant.
According to a first method of utilizing the partially evacuated vessel, the interior of the vessel is initially communicated with the interior of the suction line portion during operation of the air conditioning system, representatively using a refrigerant recharge hose assembly, whereupon the greater vacuum pressure in the suction line portion of the refrigerant circuit draws the additive liquid into the suction line portion.
According to a second method of utilizing the partially evacuated vessel, the refrigerant circuit is emptied and a vacuum pressure is created therein which is greater than the vacuum pressure within the vessel. The vessel is then communicated with the interior of the refrigerant circuit, representatively using a refrigerant recharge hose assembly, whereupon the greater vacuum pressure within the emptied refrigerant circuit draws the additive fluid into the refrigerant circuit.
Accordingly to a third method of utilizing the partially evacuated vessel, the interior of the vessel is initially communicated with the interior of the suction line portion, representatively using a refrigerant recharge hose assembly, while the air conditioning system is turned off and a positive pressure exists in the interior of the suction line portion. The positive pressure within the suction line portion forces refrigerant therefrom into the vessel, thereby positively pressurizing its interior. Next, the air conditioning system is turned on to create a negative pressure within the suction line portion, thereby drawing the refrigerant and additive liquid from the positively pressurized canister interior into the suction line portion.
The provision and use of the specially designed partially evacuated vessel provides a variety of advantages over conventional pressurized canisters containing refrigerant and liquid additive. For example, since there is no refrigerant in the vessel, the same additive liquid-containing vessel can be used with a wide variety of air conditioning or refrigeration systems that utilize different type of refrigerantsxe2x80x94the vessel does not have to be xe2x80x9cmatchedxe2x80x9d to a particular type of refrigerant in a circuit in order to avoid contamination thereof by a different type of refrigerant within the vessel.
Moreover, since refrigerant is not packaged within the vessel, the material cost of the partially filled vessel is substantially reduced. Additionally, since there is no refrigerant disposed within the as-manufactured vessel it cannot leak refrigerant into the atmosphere, and the lack of pressurized refrigerant within the as-manufactured vessel renders it safer to ship and store.
The present invention also includes a method for dehydrating refrigeration systems as well as a method for sealing metal and rubber parts in a refrigerant system. This is accomplished by the invention by using a azeotrope like material with at least 2 to 3 or more additives which are needed by modem air conditioning systems. The invention also includes a method of dehydrating and passivating the refrigerant systems having a fluid enclosure. The method comprises adding a single additive mix maintained in a binding azeotrope like material which allows the treatment of a refrigerant system for many purposes including metal and rubber sealing, dehydration and the like. In a one step application, for example, in R134a systems. The composition containing multiple additives and an azeotrope type mixture is allowed to react with interior surfaces of the enclosure of the refrigerant system to passivate, coat the surfaces as well as dehydrate the whole refrigerant system thus completing a one application treatment for the refrigerant system. An azeotrope or azeotrope mixture of refrigerant additives for sealing both rubber and metal surfaces within a refrigeration system which also dehydrates the system simultaneously because of the dehydrator which is present and is also included in the common container. The compositions include various elements which combine and operate within the binding azeotrope to deliver from a one container or one mix the desired amount of each sealing, dehydrating and treatment of refrigerant systems.